WO2005039027A2

WO2005039027A2 - Apparatus for generating sine waves of electromotive force

Info

Publication number: WO2005039027A2
Application number: PCT/US2004/032593
Authority: WO
Inventors: Herbert Pardo
Original assignee: Herbert Pardo
Priority date: 2003-10-06
Filing date: 2004-10-04
Publication date: 2005-04-28
Also published as: US7375489B2; WO2005039027A3; US20070182274A1

Abstract

An apparatus generates sine waves of electromotive force (i.e. alternating current) from a battery (21). The battery (21) includes a given number of cells connected in series. A stator and commutator (3) is formed of a multiple of segments (31). Each of the segments (31) is connected in sequence to a respective cell of the battery (21). The apparatus can be incorporated in a rotary switching device that further includes a rotor (4) having at least one brush contacting the segments of the stator and commutator (3) to carry a step waveform approximating a sine wave. The rotary switch can be included in various setups to provide a backup or alternate generator that provides alternating current.

Description

Apparatus for Generating Sine Waves of Electromotive Force, Rotary Switch Using the Apparatus, and Generators Using the Rotary Switch

Cross-Reference to Related Applications This application claims the priority of co-pending U.S. non-provisional patent application Serial Number 10/680,422, filed on October 6, 2003.

Background of the Invention Technical Field The present invention relates generally to alternating-current (AC) power generators operating from batteries and, more particularly, to an apparatus for generating sine waves of electromotive force, a rotary switch using the apparatus, and generators using the rotary switch.

Background Art Auxiliary power systems based on batteries provide backup electrical current when normal power is interrupted or unavailable. In an article entitled "How Emergency Power Systems Work" (HowStuff orks, Inc. 1988), Marshall Brain broadly describes the operation of such systems. As described in the article, batteries are the power source in one of the main types of backup power supplies. Batteries are charged with, and produce, direct current. In contrast, most public electrical utilities provide alternating current due to limitations of direct current. In addition, most appliances utilize alternating current. To make the power from batteries usable by household appliances, inverters are used to convert direct current (DC) to alternating current (AC). However, inverters are relatively expensive, primarily because they incorporate semiconductors, such as Insulated Gate Bipolar Transistors (IGBTs), which are expensive to manufacture. Inverters utilizing semiconductors cannot be used with reactive loads because the reactive loads tend to quickly burn out the semiconductor component. Furthermore, the semiconductors generally have a limited lifespan. Due to their short lifespan and relatively high manufacturing expense, inverters tend to be impractical for extended use. Like batteries, power created from alternators cannot be used to directly power household appliances. Alternators connected to an internal combustion engine produce pulsating direct current. Such direct current is suitable for charging a battery. However, pulsating current cannot be used to power appliances that are configured to run on alternating current. Generators connected to internal combustion engines are not practical for producing alternating current for household appliances. Generators connected to internal combustion engines rely on fuel. In many applications where electrical utilities are unavailable, so to is the fuel needed to power internal combustion engines. Furthermore, voltages output by the generator are directly dependent upon on the rotations per minute (rpm) of the motor. In addition, it is well known that the efficiency of such generators is limited by the electromotive effect. In U.S. Patent No. 1,691,986, issued to Nyquist, an apparatus and a method for generating pure sine waves of electromotive force is disclosed. Nyquist teaches to connect a battery producing a single voltage to two "distributors," which are formed by a resistor system. The resistor system is formed using two potentiometer resistors, a respective one connected to each terminal of the battery. Then, multiple taps, which are each resistors, connect at various points along the potentiometer resistor to a respective segment of a stator and commutator (i.e., "tributor ring"). A rotor can then be turned within the stator and commutator to produce an alternating sine wave. As shown in FIG. 2 of Nyquist, the resulting waveform has an uneven step-up; that is, the height of each step near the baseline is shorter than a corresponding step near the apex of the wave. In addition, because the system utilizes resistors, the output voltage of the sine wave is dependent upon the resistance of the load and the resistance of the circuit. Consequently, the output voltage is variable.

Disclosure of Invention It is accordingly an object of the invention to provide an apparatus for generating sine waves of electromotive force, a rotary switch using the apparatus, and generators using the rotary switch, which overcome the aforementioned disadvantages and limitations of existing devices of this general type, and which generate a sine wave with low and high power, for the purpose of supplying AC power for all types of equipment requiring single- and three-phase electrical power. Accordingly, there is provided, in accordance with the invention, an apparatus for generating sine waves of electromotive force. The apparatus includes a battery, a stator and a commutator. The battery includes a desired predetermined number of cells connected in series. The stator and commutator are formed by a multiple of segments, wherein the multiple is equal to the desired predetermined number of cells 21 multiplied by a natural number (i.e., n = 1, 2, 3...). For example, if there are twenty (20) cells, there could be twenty (20), forty (40), sixty (60), etc. segments. Each of the segments is connected sequentially to a respective one of the cells. The reason for this is that the electric potential at each of the cells is affected by the respective neighboring, or adjacent, cells. The midpoint of the battery cells has a zero-potential. The cells at one of the ends have a positive potential that increases with distance away from the midpoint. The cells at the other end have a negative potential that decreases, or becomes increasingly negative, with distance away from the midpoint. The cells are then connected in sequence to segments of the wheel. In instances where the number of segments is two or more times the number of cells, the segments are connected to the cells to create, in the stator and commutator, a potential having ascending positive voltages, descending positive voltages, descending negative voltages, and increasing negative voltages. A rotary switch can be manufactured that includes the above-described apparatus.

The rotor turns concentrically within the stator and commutator, and incorporates a brush that contacts the segments of the stator and the commutator when the rotor turns. Significantly, the brush is manufactured such that it does not "stretch" while turning, from the centrifugal force, and cause wearing of the segments. The present invention incorporates various embodiments utilizing varying quantities of brushes on the rotor. Where a single brush is used, a counterbalance should be incorporated to offset the weight of the brush. Where multiple brushes are incorporated, the brushes should be distributed equally, or equidistantly spaced, about the rotor in order to maintain the rotational balance of the rotor. Even distribution of the brushes about the stator results in a corresponding symmetric waveform. In accordance with a further object of the invention, the number of sets of segments, the number of brushes and the rotational speed of the rotor, can all be selectively adjusted to modify the resulting waveform. Generally, the number of segments and brushes will be chosen to limit the required speed of the motor to a speed that is physically feasible and commercially available; that is, to a speed within the operational specifications of commercially available motors. In accordance with a further object of the invention, the quantity of brushes and segments can be chosen to produce multiple phased waveforms. For example, if three- phased output is desired, one set of segments, and a rotor with three evenly spaced brushes, can be used. This will result in an evenly spaced three-phase waveform. To conduct the signal received by each brush, a respective slip ring is connected to the brush. The slip ring is also connected to an output. Preferably, the electrical ground for the output is connected to the midpoint of the battery bank, where there is zero potential. In accordance with a further object of the invention, an electric motor is connected to the axis of the rotor to initiate rotation. Furthermore, a starter is preferably connected to the motor. The starter and motor can be recharged from the rotary switch, once it has started. To produce a high-powered embodiment, several stators, commutators and respective rotors, are connected in parallel to the battery. The brushes of the rotors can be configured to produce complementary waveforms, or spaced to produce different-phased waveforms. In such an embodiment, the multiple rotors can be placed on a single axle. In accordance with a further object of the invention, the above-described rotary switch can be used as a backup generator in a house that normally uses an electric utility to provide alternating current. In such applications, the electric utility connects to a transfer box, which in turn, connects to the house at a main breaker. If power from the electric utility is interrupted, the rotary switch powered by the battery operates to provide alternating current to the house. During normal operation of the electric utility, the electric utility recharges the battery bank. Even in a house that uses alternating current but is not connected to an electric utility, a generator according to the invention can be used to provide alternating current for the house. The rotary switch has its output connected to the fuse box of the house. To charge the battery of the rotary switch, a battery charger is connected to the battery. The battery charger can be any typical charger, but preferably includes a solar panel, an alternator and an internal combustion engine. Although the invention is illustrated and described herein as embodied in an apparatus for generating sine waves of electromotive force, a rotary switch using the apparatus, and generators using the rotary switch, it is, nevertheless, not intended to be limited to the details shown since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

Brief Description of the Drawings FIG. 1 is a schematic front view showing a stator and commutator with internal connections, and a battery for producing two periods per rotation according to the invention; FIG. 2 is a diagrammatic cutaway side view showing an internal surface of the stator and commutator shown in FIG. 1; FIG. 3 is a waveform showing a single-phase output produced by one-half of a turn around the stator and commutator shown in FIG. 1; FIG. 4 is an exploded diagrammatic view of a setup having one brush on the rotor; FIG. 5 is a diagrammatic front perspective view showing the stator and commutator from FIG. 1 ; FIG. 6 is a diagrammatic front view of the stator and commutator shown in FIG. 3; FIG. 7 is a front view of the setup shown in FIG. 4; FIG. 8 is a front view of a rotary switch utilizing a rotor with two brushes; FIG. 9 is a waveform showing the two-phase output produced by the setup shown in FIG. 10; FIG. 10 is a left side view showing a setup having a rotor with two brushes; FIG. 11 is an exploded side view showing the setup from FIG. 10 with the rotor separated from the stator and commutator; FIG. 12 is a front view of a rotary switch having a rotor with one brush and a counterbalance; FIG. 13 is a front view showing a rotary switch having three brushes; FIG. 14 is a diagrammatic left side view of a setup using the rotary switch shown in FIG. 13; FIG. 15 is an exploded left side view of the setup shown in FIG. 14 with the stator and commutator separated from the rotor; FIG. 16 is a three-phase waveform produced by the setup according to FIG. 14; FIG. 17 is a front view of the rotor used in the setup shown in FIG. 14; FIG. 18 is a left-side view of the rotor used in the setup shown in FIG. 14 with the connections from the brushes to the slip rings shown in phantom; FIG. 19 is a left side view of a setup utilizing three stator and commutator/rotor pairs; FIG. 20 is a front side view of one of the pairs of the stator and commutator and rotor shown in FIG. 19; FIG. 21 is a front view of the stator and commutator shown in FIG. 1, without the internal connections; FIG. 22 is graph plotting the voltages versus the perimeter of the stator and commutator shown in FIG. 21; FIG. 23 is a block diagram of an emergency generator utilizing the rotary switching device according to the invention; FIG. 24 is a block diagram of an AC generator recharged by an alternator; and FIG. 25 is a block diagram of a generator recharged by a solar panel.

Modes for Carrying Out the Invention Referring initially to FIG. 14, a setup 1 is shown for producing a three-phase waveform (as shown in FIG. 16). The setup 1 includes a battery power supply 2. For illustrative purposes, the battery power supply 2 is shown as a plurality of cells 21 connected in series. The battery power supply 2 is connected to a stator and commutator 3. As shown in FIG. 15, a rotor 4 with three brushes 5 turns within the stator and commutator 3. The three brushes 5 each pick up a sine-shaped voltage waveform. The combined waveform is therefore a three-phase waveform. Each phase is conducted from one of the brushes to a respective slip ring 6. From the slip rings 6, the current is transferred to the output 9. To initiate the turning of the rotor 4, a starter 7 and motor 8 are connected mechanically to the axle 42 of the rotor 4. Referring now particularly to FIGS. 1, 2, and 21 the battery 2, and the stator and commutator 3, are shown in detail. The battery 2 is formed from a plurality of cells 21 connected in series. The series connection provides different voltage levels at the taps where each cell is connected to the next adjacent cell. A neutral point, N, is defined at the midpoint of the battery 2. As shown in FIG. 1, one side of the battery 2 has a voltage in a first direction A+, and the other side of the battery has a voltage in an opposite direction A-. The stator/commutator 3 is comprised of a wheel constructed from conductive segments 31 that are electrically insulated from each other. Preferably, the segments 31 are constructed from copper. An insulative ring surrounds the outside of the stator and commutator and supports the segments 31. Preferably, the number of cells 21 is a whole number ratio (e.g., 3:1, 2:1, 1 :1, 1:2, 1:3, etc.) vis-a-vis the number of segments 31. In a most preferred embodiment, the number of segments 31 is two-times the number of cells 21. The battery power segments 31 are connected in the sequence of the cells 21. The result is a stepped voltage approximating a sine wave, as best shown in FIG. 22. The number of steps in the sine wave equals the number of segments 31 in the stator and commutator 3. Therefore, the more segments 31 that are provided, the more accurately the stepwise approximation will approach a sine wave. The electrical ground for the sine wave is connected to the neutral point N of the battery 2. To reduce the required speed of the rotor to create a desired frequency, additional brushes 5 can be added to the rotor, and the multiple of segments 31 can be increased. In the stator and commutator 3 shown in FIG. 1, the multiple is two; that is, two complete phases are produced per turn of the rotor 4. As shown in FIG. 1, the segments 31 of the stator are connected to have an increasing positive voltage (I), a decreasing positive voltage (II), a decreasing negative voltage (III) and an increasing voltage (IV). These voltages can be plotted to the waveform shown in FIG. 3. The purpose of the stator and commutator 3 is to supply a sequence of increasing, and then decreasing, DC voltage to the brushes 5 of the rotor 4. As the brushes 5 rotate and contact the segments 31 in sequence, an increasing, then decreasing, voltage is created over time. The voltage, when plotted versus time, has the form of a sine wave. As best shown in FIG. 13, the rotor 4 rotates concentrically within the stator and commutator 3. Referring now to FIGS. 3, 4, 7 and 12, in another embodiment of the present invention, the rotor 4 has a single brush 5. The brush 5 contacts the various segments 31 of the stator and commutator 3 as the rotor 4 turns. The rotor 4 rotates on a steel shaft 42. To initiate turning of the rotor 4, a starter 7 and a motor 8 are connected to the steel shaft 42. A counterbalance 51 is added to maintain a balanced rotation. In a preferred embodiment, the rotor 3 is a solid wheel 41 that rotates on a steel shaft 42. An electric motor 8 with a starter 7 is included to initiate turning of the rotor 3. A slip ring 6 is connected to the brush 5. In turn, the slip ring 6 is connected to the output 9. Referring now to Figures 8, 9, 10 and 11, in a further embodiment of the invention the rotor 4 has two (2) brushes 5. Preferably, the brushes 5 are distributed evenly about the perimeter, or circumference, of the rotor 4. By distributing the brushes 5 in such an evenly spaced manner, a dual waveform, as shown in FIG. 9 can be produced. The brushes 5 contact the various segments 31 of the stator and commutator 3 as the rotor 4 turns. The rotor 4 rotates on a steel shaft 42. To initiate turning of the rotor 4, a starter 7 and a motor 8 are connected to the steel shaft 42. Preferably, the rotor 3 is comprised of a solid wheel 41 rotating on a steel shaft 42. An electric motor 8 with a starter 7 is provided to initiate turning of the rotor 3. Each brush 5 is connected to a respective slip ring 6, and the waveform is carried to the slip ring 6. Likewise, the slip ring 6 is connected to the output 9. In the embodiment shown in FIG: 17, three brushes 5 are distributed about the perimeter of the wheel 32. To distribute the phases to be created, the brushes 5 are spaced equidistantly about the wheel 32. As each of the brushes 5 rotates against the stator and commutator 3, a sine wave is created. The frequencies of the three resultant waveforms are equally out of phase with each other by one-third of a period. The three waveforms are shown in FIG. 16. As shown in FIG. 18, the shaft 33 has three slip rings 6. A current from each of the brushes 5 is carried to a respective slip ring 6. From the slip ring, the current is connected to the output 9, where it can be used to power any typical device. Figure 19 shows an embodiment that produces increased power. In this embodiment, the battery 2 is as described above. Three stators and commutators 3 a, 3b, and 3 c are connected in parallel to the battery 2. Respective rotors 4a, 4b, and 4c (hidden in the view of FIG.19) rotate on a common axis 42. The rotors 4a, 4b, and 4c could include one, two, or three brushes 5. In the embodiment shown in FIG. 20, three brushes 5 are provided. Each of the brushes 5 of each of the rotors 4a, 4b, and 4c are connected to a respective slip ring 6a, 6b, or 6c. The slip rings 6a, 6b, and 6c, are connected to output 9. Preferably, the electric motor 7 is a direct current (DC) power unit with rpm control in order to maintain a constant rpm. The motor 7 has a light load. The purpose of the motor 7 is to turn the rotor(s) 4 in the stator and commutator 3. The rpm (revolution per minute) of the motor 7 determines the frequency of the output signal according to the following equation:

RPM = (60sec/min)(frequency) / (multiple) In this equation, "multiple" refers to the multiple of cycles per revolution, and

"frequency" is the desired frequency, typically 60 Hz. Figure 23 shows a setup 1 being utilized as a back-up generator for a house 104 receiving alternating current (AC) under normal conditions from an electric company 108.

Normally, current from the electric company 108 reaches a main breaker 107 that is connected to a transfer box 106 of the house 104. During normal operation, electricity from the electric company 108 recharges the battery 2 via the battery charger 100. In an alternate embodiment, the battery charger 100 can be an internal combustion motor ' connected'ttTa-ft altern-ϊtόϊ. "As described above, the battery 2 powers the rotary switching device (RSD) of the setup 1 and outputs power to the transfer box 106. If power from the electric company is interrupted, the setup 1 feeds alternating current for the house 104 via the transfer box 106. Figure 24 shows the connections used to apply the setup 1 in a typical power generator. In this case, a battery charger 100 is formed simply by a motor 101 connected to an alternator 102. In turn, the alternator 102 is connected to, and charges, the battery 2. The setup 1 is connected to the fuse box 103 of the particular structure (e.g., house or business). The fuse box 103 distributes electricity throughout the structure 104. Figure 25 shows the setup 1 being used with solar panels 105. Solar panels 105 are connected to the battery 2 and provide direct current to the battery 2 for charging the battery. As before, the setup is connected to the fuse box 103 where electricity is distributed to the house 104. Since many modifications, variations, and changes in detail can be made to the described preferred embodiments of the invention, it is intended that all matters in the foregoing description and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense. Thus, the scope of the invention should be determined by the appended claims and their legal equivalence.

Claims

What is claimed is:

1. An apparatus for generating sine waves of electromotive force, comprising: a battery including a given number of cells connected in series; and a stator and commutator formed of a multiple of segments, the multiple equaling said given number of cells multiplied by a natural number; each of said segments being connected sequentially to a respective one of said cells.

2. The apparatus according to claim 1, wherein said natural number is at least two and said segments are in order of ascending positive voltages, descending positive voltages, descending negative voltages, and increasing negative voltages.

3. A rotary switch, comprising: a battery including a given number of cells connected in series; a stator and commutator formed of a multiple of segments, the multiple equaling said given number of cells multiplied by a natural number, each of said segments being connected sequentially to a respective one of said cells; and a rotor having a brush and turning concentrically within said commutator with said brush contacting said segments.

4. A rotary switch, comprising: a battery including a given number of cells connected in series; a stator and commutator formed of a multiple of segments, the multiple equaling said given number of cells multiplied by a natural number, each of said segments being connected sequentially to a respective one of said cells; a rotor turning concentrically within said commutator; and a number of brushes disposed on said rotor and contacting said segments.

5. The rotary switch according to claim 4, wherein said number of brushes equals a number of desired phases.

6. The rotary switch according to claim 4, wherein said brushes are evenly distributed about said rotor.

7. The rotary switch according to claim 4, further comprising a counterbalance disposed on said rotor opposite said brush.

8. The rotary switch according to claim 4, further comprising a slip ring on said axis connected to said brush. .

9. The rotary switch according to claim 6, further comprising a number of slip rings equaling said number of brushes, each one of said slip rings being connected to a respective one of said brushes.

10. The rotary switch according to claim 4, further comprising: an electric motor connected to said axis of said rotor; and a starter connected to said electric motor.

11. A rotary switch comprising: a battery including a given number of cells connected in series; a plurality of stators and commutators each formed by a multiple of segments, said multiple equaling said given number of cells multiplied by a natural number, each of said segments being connected sequentially to a respective one of said cells, and said stators and commutators being connected in parallel to said battery; and a respective rotor for each of said stators and commutators, each having a brush and turning concentrically within said commutator with said brush contacting said segments.

12. The rotary switch according to claim 11, wherein said rotors are coaxial.

13. In a house using alternating current and having a transfer box connected to a main breaker of an electric utility, an emergency generator comprising: a rotary switch, comprising: a battery including a given number of cells connected in series; a stator and commutator formed of a multiple of segments, the multiple equaling said given number of cells multiplied by a natural number, each of said segments being connected sequentially to a respective one of said cells; a rotor having a brush and turning concentrically within said commutator with said brush contacting said segments; an output connected to the transfer box; and a battery charger interconnecting the main breaker to said battery and configured to convert alternating current from the electric utility to direct current for charging said battery.

14. In a house using alternating current and having a fuse box; a generator comprising: a rotary switch, comprising: a battery including a given number of cells connected in series; a stator and commutator formed of a multiple of segments, the multiple equaling said given number of cells multiplied by a natural number, each of said segments being connected sequentially to a respective one of said cells; a rotor having a brush and turning concentrically within said commutator with said brush contacting said segments; an output connected to the fuse box; and a battery charger connected to said battery and configured to provide direct current for charging said battery.

15. The generator according to claim 14, wherein said battery charger includes an alternator and motor turning said alternator.

16. The generator according to claim 14, wherein said battery charger includes a solar panel.